1. Field of the Invention
This invention relates to a method of processing an iron-containing dust obtained in the preparation of iron or steel.
2. Description of the Prior Art
An iron-containing dust of this type is obtained, for example, by collecting blast-furnace dust which escapes from blast-furnaces and containing iron, zinc and lead. The latter two metals are a consequence of the presence of small quantities of zinc lead which occur as impurities in the iron ore.
On the other hand, a similar iron-containing dust is obtained, usually in the form of wet waste dust, by collecting the dust escaping from steel works, which also contains a considerable quantity of zinc. This zinc originates from the paint coating or galvanized protective coating on the scrap added to the molten iron in the steel works.
This iron-containing dust is a considerable nuisance to the iron or steel manufacturing industry, because, notwithstanding the high iron content, this iron-containing dust cannot be reused in iron manufacture because of the large quantities of zinc. The iron-containing dust obtained from a blast-furnace in fact contains 0.8% zinc and 36% iron, while the zinc percentage in the dust collected from steel works is 1.5% and the iron content 60%.
Because of the impossibility of recycling these products to the blast-furnaces or steel works, this iron-containing dust therefore has to be stored, and this involves considerable areas being occupied while the presence of the zinc readily results in an undesirable pollution of the environment due to the leaching out of the zinc. This holds the more if, for example, in addition to the zinc very small quantities of cadmium are present in the iron-containing dust.